China’s cyber spies have accessed the private emails of “many” top Obama administration officials, according to a senior U.S. intelligence official and a top secret document obtained by NBC News, and have been doing so since at least April 2010.

The email grab — first codenamed “Dancing Panda” by U.S. officials, and then “Legion Amethyst” — was detected in April 2010, according to a top secret NSA briefing from 2014. The intrusion into personal emails was still active at the time of the briefing and, according to the senior official, is still going on.

In 2011, Google disclosed that the private gmail accounts of some U.S. officials had been compromised, but the briefing shows that private email accounts from other providers were compromised as well.